1. Field of the Invention
This invention relates to heat exchangers for transferring heat energy between two separate fluids. More particularly the present invention relates to a wrapped fin heat exchanger having a fin material wrapped about a tube to form an enhanced heat transfer surface. As set forth herein a continuous length of fin tubing is wrapped into a generally cylindrical configuration and has portions thereof wrapped about other portions to maintain the tubing in the selected configuration.
2. Description of the Prior Art
It is known to manufacture a heat transfer surface formed by having a base tubular member fabricated from aluminum or another heat transfer material and having a fin material helically wound about the base member. This fin material may be formed in a U-shape and wrapped about the tube with the base of the fin contacting the exterior surface of the base tube to form a metal to metal contact promoting heat transfer from the tube to the fin. By this extended fin surface it is possible to provide increased heat transfer between the fluid flowing through the tube and a gaseous substance flowing over the tube. A fin surface of the type described is disclosed in U.S. Pat. No. 3,134,166 issued to Venables.
This wrapped fin tubing is specifically formed into a geometrical configuration in conjunction with a heat exchange unit and a fan for circulating air thereover. A heat exchanger of this material has many applications. A typical application would be in a refrigeration circuit for an air conditioning system wherein refrigerant flows through the tube and air flows over the exterior enhanced portion of the heat exchanger. In these applications heat energy is transferred between the air flowing over the exterior and in contact with the wrapped fins and the refrigerant flowing through the interior of the tube. A heat exchanger may be formed in many configurations to provide the appropriate air flow relationship thereover. A fan is typically mounted as part of an air conditioning unit for drawing air through or pushing air over the heat transfer surface. The heat exchanger typically is configured to promote air flow as directed by the fan over the heat exchange surface.
One of the many configurations possible for a heat exchange unit of this type is a cylinder. When a long continuous tube is wrapped into a generally cylindrical configuration there is little inherent support within the structure. The tube may be wound about a drum in a helical manner to form the primary heat exchange surface. Upon removing the tubing from the drum there is a tendency of the tubing to unwind and collapse. The handling of the heat exchanger in this configuration becomes particularly difficult since the degree of unwinding or other change from the form wrapped about the drum is unpredictable and the person doing such handling must accommodate such changes.
One way to prevent the heat exchanger from changing dimension when removed from the drum is to provide a structural support mechanism which secures the individual loops of tubing into the desired configuration. This structural arrangement may be mounted to the heat exchanger before removal from the drum.
Another manner in which the structural integrity of the heat exchanger may be maintained is as disclosed herein by the use of a locking portion formed by wrapping tubing in a reverse helical direction over the core portion of the heat exchanger such that the bands wound in the reverse direction interlock with the loops wound in the first direction to maintain the structural integrity of the heat exchanger.